Web cutting apparatus

ABSTRACT

Transverse cuts are made in a web using a cutter/anvil combination which is subjected to high frequency vibration, preferable ultrasound. In one arrangement, particularly for cutting tea bag webs, a rotary cutter drum (4) cooperates with an ultrasonically-vibrated anvil 12. The web may be simultaneously sealed and cut by means of a modified drum (202) having sealer/cutter elements (208, 210). In other arrangements, particularly for cutting cork paper on a machine for assembling filter cigarettes, the paper is severed on a drum (106, 122, 192, 350) cooperating with an ultrasonically-vibrated anvil (110, 194, 312) or directly on an ultrasonically-vibrated drum (144, 160, 170, 180).

This invention relates to web cutting apparatus, particularly but notexclusively as employed for severing webs in packaging or wrappingprocesses.

According to one aspect of the invention apparatus for making successivelongitudinally spaced cuts in a web comprises means for moving the web,means for periodically bringing a cutter into the region of the web, andmeans for producing high frequency relative vibration between the cutterand the web, so that the cutter makes at least one cut, having at leasta portion extending in a transverse direction of the web. The vibrationmay have a primary amplitude transverse to the web, either in itsthickness direction or across its width, or its primary direction may belongitudinal relative to the web. Preferably the cutter cooperates withan anvil (which term is used herein to include any counter surface) andthe vibration producing means produces relative vibration between thecutter and the anvil. Preferably the vibration producing means comprisesan ultrasound generator. In a preferred arrangement the anvil issubjected to ultrasound vibration, although the cutter itself may bevibrated, either in a direction across the web width (i.e. in a sawingaction) or in a direction parallel to the thickness of the web (in acrush-cut action).

The cutter is preferably moved with the web, (e.g. by being mounted on aroller), although it need not move at the same speed as the web. Theanvil may be stationary (apart from the generated vibration) or may movewith the web or the cutter, although again not necessarily at the samespeed. The device may be arranged to sever portions of the web from theremainder of the web, e.g. by severing successive leading portions.Where the anvil is a movable member, e.g. a rotary drum, sectionssevered from the web may be subsequently conveyed on the anvil.Alternatively, where the cutter is mounted on a movable member thesevered sections could be subsequently conveyed on the member.

In one application the invention is embodied in a machine for producingpackages containing tea or other infusible material. Thus, a double plyweb containing spaced portions of infusible material may be subjected tocutting by a device according to the invention in which the cutter has acutting edge which surrounds the portion of infusible material and cutsit out from the web. The cutting edge may thus define the shape of thepackage containing infusible material produced from the web. It will beunderstood that the edges of any such package have to be sealed toprevent the infusible material escaping. Sealing may be carried out byrollers or other suitable means arranged upstream of the cutting deviceand synchronised with it so that the web is cut in a region such thatthe cut edge or edges of the packet are separated from the infusiblematerial by a sealed portion of web.

As an alternative to providing such separate sealing means, and inaccordance with another aspect of the invention, a cutting device (whichmay be, but is not necessarily, constructed in accordance with said oneaspect of the invention) comprises means for performing a sealingoperation on an adjacent portion of the web substantially simultaneouslywith the cutting operation. In this case, the device preferably performssealing and cutting with the assistance of ultrasound. A suitablecutting and sealing element, which could be carried by a rotary drum forcooperation with a stationary ultrasonically-vibrated anvil comprises arelatively flat portion for sealing and a relatively narrow edge portione.g. abutting the flat portion, for cutting. Preferably the sealingportion is arranged to contact a downstream portion of the web relativeto the cutting edge. Where sealing and cutting are carried out inseparate processes with the sealing operation performed on the webupstream of the cutting operation, in order to provide adequatetolerance for registration at the cutting operation the sealing widthmay need to be wider than strictly necessary to provide an adequateseal. By combining the cutting and sealing operations, problems ofregistration are avoided and there is a potential materials saving byreducing the width of the seal.

It is preferable to control the relative spacing between a cutter andanvil for effective cutting of a web of predetermined thickness. In adevice for cutting a two ply web of heat-sealable filter paper formaking tea bags, having a thickness of web to be cut of about 0.075 mm,a mean spacing between a rotary cutter having a diameter of about 135 mmand a stationary anvil of about 0.04 mm has been found to be effectiveusing an ultrasonic generator which produced ultrasound vibrations inthe anvil having an amplitude (peak to peak) of about 0.07-0.08 mm in adirection transverse to the web. A preferred frequency for theultrasound vibration is 20 kHz. Higher frequencies (e.g. 40 kHz) areusable and may be desirable for very high speed operation butmaintaining adequate amplitude of vibrations at higher frequencies usesmore power. Frequencies lower than 20 kHz (i.e. below those normallyrecognised as ultrasound) may be used, but particularly with high speedmachinery the advantages gained by providing vibration at lowerfrequencies, as compared with providing no vibration, may be marginal.With the arrangement described above, with a web speed of about 1.2meters/second, the web is subjected to 30-40 cycles of ultrasonicvibration while the knife is in contact with it.

Means may be provided for adjusting the spacing between an anvil and acutter, preferably by sensing the distance between the anvil and cutter(or parts movable with them) and by moving the anvil in response to thesensed distance. In practice it may be difficult to obtain measurementsdirectly from a member which is subject to vibration; the adjustingmeans may therefore include control means (which may include software)for adjusting the spacing according to parameters which relateindirectly to the spacing. Thus, adjustment could be made according to amapped position profile against time after start up to compensate forthermal expansion, or against a number of cuts made to compensate forwear in the cutter and/or anvil.

The spacing between the anvil and the cutter may be set by spacingmeans. In a preferred arrangement wherein the cutter is carried on arotary drum, the spacer means comprises one or more control ringscarried by the drum and arranged so that their circumference is at aradius from the axis of the drum which bears a predeterminedrelationship to the radius at which the cutting edge of the knife iscarried. The rings could have the same radius as that of the cuttingedge of the knife, so that the control rings maintain the anvil at adistance from the general surface of the knife drum which is equal tothe radial distance by which the knives project from that surface. Theanvil, which may be stationary or could comprise a further drum, and theknife carrying drum may be resiliently urged together, with the controlrings setting the spacing between the anvil and the drum, and hencebetween the anvil and the knives.

In another application of cutting apparatus according to the invention,the apparatus is employed in a machine for assembling filter cigarettes,for cutting the filter tipping paper (so called "cork" paper) which iswrapped around axially aligned assemblies of filter and tobacco rods toproduce filter cigarette assemblies.

In one preferred arrangement a web of filter tipping paper is deliveredat a controlled speed to a suction and cutting drum which is rotating ata faster speed than the web, the drum carrying knives which cooperatewith a vibrating anvil to sever successive leading sections of thefilter paper. These sections are subsequently conveyed on the drumtowards a rolling plate at which they are wrapped and united around thefilter and tobacco rods. A similar arrangement is usable to unite otherrod-like articles of the tobacco industry.

Adhesive may be applied to the web upstream of the drum, to either faceof the web. Where the adhesive is on the face of the web which contactsthe anvil the latter will probably require cleaning means to removeadhesive which is transferred to it from the web. Where the adhesive isapplied to the surface of the web which contacts the suction and cuttingdrum, the adhesive is preferably applied to the web in a pattern whichleaves regions with no adhesive, the suction ports on the drum beingarranged to coincide with these regions so as to minimise transfer ofadhesive to the drum. Cleaning means, such as a brush and/or suction,may be provided for the drum. Where the wrapper sections are carried onthe drum with the adhesive outermost the sections may be supplieddirectly to the region of a rolling plate for uniting the filtercigarette assemblies. In order to prevent damage occurring to theassemblies at the rolling plate from the protruding knives of the drumthe knives may be arranged to be retractable, e.g. by mounting them onradial slides operated by a central cam.

Instead of applying adhesive to the web the adhesive could be applied tothe sections after cutting: this would have the advantage of eliminatingthe need to clean the anvil but would involve a more complicatedadhesive applying means which is capable of applying adhesive to spacedsections on the drum.

Instead of using a stationary anvil a rotary ultrasonically vibratedanvil may be used. The vibrations set up in the anvil may, according toits design, be radial or circumferential. In either case the anvilpreferably cooperates with a drum carrying the or each cutter. Severedwrapper sections may be conveyed away on the rotary anvil or on thecutter drum. Where a rotary anvil is employed a central or coreultrasound generator may cooperate with a number of generally radialspokes forming ultrasound boosters the ends of which form the anvilsurfaces against which the cutter or cutters operate. Conveniently thisform of rotary anvil may comprise a drum with the end faces of thespokes flush with the general circumference of the drum.

The invention will be further described, by way of example only, withreference to the accompanying diagrammatic drawings, in which:

FIG. 1 is a part-sectional view of a web cutting device taken along aline transverse to the web,

FIG. 2 is a part-sectional view of the device of FIG. 1 taken along aline parallel to the web,

FIG. 3 is a view, similar to that of FIG. 1, of a modified web cuttingdevice,

FIG. 4 is a view, similar to that of FIG. 2, of the device of FIG. 3,

FIG. 5 is a view on the line V--V in FIG. 4,

FIG. 6 is a side view of another web cutting device,

FIG. 7 is a side view of a further web cutting device,

FIG. 8 is plan view of a web in the device of FIG. 7, showing the gummedareas of the web,

FIG. 9 is a side view of a further web cutting device,

FIG. 10 is a side view of a modified roller for use with the device ofFIG. 9,

FIG. 11 is a side view of a further web cutting device,

FIG. 12 is a side view of a still further web cutting device,

FIG. 13 is a transverse sectional view of a modification of the webcutting device of FIG. 7,

FIG. 14 is a side view of part of a web cutting and sealing device,

FIG. 15 is a part-sectional view of a modified roller for use in a webcutting device,

FIG. 16 is a view, similar to that of FIG. 1, of a further modified webcutting device, and

FIG. 17 is a view, similar to that of FIG. 2, of the device of FIG. 16.

FIGS. 1 and 2 show a web cutting device for use in a machine for cuttingout round bags from a two-ply web 2 having spaced portions containingtea or other infusible material. The general construction and operationof the machine forms no part of this invention but reference is directedto PCT patent specification No. WO 90/13487 for details of a machinewith which the device is usable.

The web 2 is conveyed beneath a cutting roller 4 which is provided withrecesses 6 surrounded by raised cutting edges 8. The web 2 is maintainedunder tension and conveyed past the roller 4 by nip rolls 10 which aresynchronised with the roller so that the speed of the web and theperipheral speed of the roller are matched. The roller 4 is synchronisedwith means (not shown) for sealing the two plies of the web 2 togetherin a peripheral region around each portion containing infusiblematerial, so that these portions coincide with the recesses 6 at theroller 4 and the peripheral regions coincide with the cutting edges 8.

An anvil 12 is situated beneath the roller 4 and has an upper face whichis spaced closely to the periphery of the roller and which provides asurface against which the cutting edges 8 operate. The anvil 12 formspart of an ultrasonic device 14, which also comprises an ultrasonicgenerator 16 containing piezoelectric material and a part 18 comprisinga booster for amplifying the ultrasound generated by the generator andfor transmitting it to the ultrasonic horn or anvil 12. A commerciallyavailable device suitable for performing the function of the device 14is Model 902R available from Branson Ultrasound of Hayes, Middlesex,England. The anvil 12 is constructed of a mechanically-suitable materialcapable of withstanding the ultrasound vibrations without suffering fromfatigue. Typically the material may be suitable alloys of titanium (e.g.Al6Va4) or aluminium (e.g. He15). Depending on its dimensions the anvil12 may have one or more longitudinal slots (not shown) extendingparallel to its axis: such slots may be required where the width of theanvil is more than about two thirds of its length. The booster 18 couldbe incorporated within the anvil 12: this has the advantage of makingthe device 14 shorter.

The ultrasound generator 16 is rigidly connected to the lower face of ahousing 20. The part 18 is connected to an internal flange 22 in thehousing 20, its mounting position being at a node relative to theprimary frequency of the ultrasound generated by the device, so thatthere is little or no relative vibration transmitted to the housing. Theanvil 12 has integral side pieces 24 each connected to the main centralpart of the anvil by upper and lower thin strips or beams 26. The sidepieces 24 are connected to a lower plate 28 which is itself connected tothe housing 20. The beams 26, which may for example be of 1 mmthickness, allow the anvil 12 to perform ultrasound vibrationstransmitted to it from the booster part 18 without transmittingsubstantial vibrations to the side pieces 24 and hence to other parts ofthe machine. In other words the beams 26 effectively isolate the anvil12 dynamically from the remainder of the machine.

The side pieces 24 have outer vertically-extending extensions 25 whichare constrained by and vertically slidable in guideways 30 provided ateach side in a structural part 32 of the machine. Each side pieceextension 25 has an extending pin 34 which is engaged by a movableelement of a linear actuator 36 connected to the part 32.

At their upper faces the side pieces 24 carry gap transducers 40 forsensing the distance between the anvil 12 and the roller 4. Thetransducers 40 may be optical or eddy current transducers. Any deviationfrom a desired distance may be corrected by operation of the linearactuators 36 to reposition the device 14 relative to the roller 4. Afteradjustment, the device 14 can be locked in position by clamping the sidepiece extensions 25 in the guideways 30 by means of pneumatic clamps 38(FIG. 2). The linear actuators 36 may include rotary encoders by meansof which the position of each actuator relating to a datum setting mayby determined.

In operation, with a web 2 having a nominal thickness of 0.075 mm, theanvil 12 is placed typically at a mean spacing of 0.03-0.04 mm from thepath of the cutters 8. The amplitude of the ultrasonic vibration istypically 0.07-0.08 mm at a frequency of 20 kHz. At a web speed of 1.2meters/second it is believed that the web is trapped and released some30-40 times per pass of each portion of cutting edge 8. As compared withoperating a cutting roller 4 in conjunction with an anvil orcounter-surface not subject to high frequency vibration the devicesignificantly prolongs useful life of the cutting edges 8, particularlyby providing an acceptable cut even when the cutting edge is relativelyblunt, while the vibration is believed to facilitate relatively smoothpassage of the web between the roller 4 and anvil 12.

The effectiveness of the cutting operation is dependent on relativelyaccurate positioning of the anvil 12. The linear actuators 36 maycomprise linear ball screws with high ratio gear boxes to providelocation of the anvil 12 which is accurate to within a few microns. Theactuators are independently adjustable, depending on signals from theposition transducers 40, so as to be capable of adjustment to maintainthe anvil parallel to the roller 4. The face of the anvil 12 whichcooperates with the cutting edges 8 is subject to wear, typically at arate of about 1 micron every 150,000 cuts. A higher wear rate may betolerated, particularly where it is desired to reduce the wear rate ofthe cutting edges 8: in such case the anvil 12 may be constructed of amaterial which is softer than titanium, e.g. aluminium. Because of theirlocation, the position transducers 40 do not detect wear: however, thecontrol circuit linking them to the actuators 36 may include means (e.g.embodied in software) for compensating for wear (e.g. by modifying themeasured distance according to the number of cuts made since a datumsetting of the relative positions of the transducers and the surface ofthe anvil 12). Similarly, the actuators may need to be controlledaccording to a mapped movement profile during start-up to compensate forchanges in relative position due to thermal expansion as the device isrun up to operating temperature: reaching a stable operating temperaturefrom rest may take up to 20 minutes. A typical running temperature forthe anvil 12 is 70° C. Effects of thermal expansion can be reduced byreducing the distance between the pins 34 (on which the positionactuators 36 operate) and the working face of the anvil 12.

The device shown in FIGS. 3-5 is similar to that of FIGS. 1 and 2, andsimilar parts have been given similar reference numbers. The maindifference between the devices lies in the mounting of the anvil 12. Inthe device of FIGS. 3-5 a rectangular housing 50 is connected to theupper surface of the housing 20 and surrounds the lower half of theanvil 12. At its upper end the housing 50 has a slot 52 through whichprojects the upper part of the anvil 12. Mounting flanges 54 areprovided on the anvil 12 and these are connected to the housing 50 onopposite sides of the undersurface of the slot 52. The flanges 54 arepositioned at a node in the ultrasound vibration generated in the anvil12, so that minimum vibration is transmitted to the housing 50. At eachside the housing 50 has rectangular extensions 56 which engage in andare slidable in the guideways 30. The housing 50 also has upwardextensions 58 at each side of its upper face, these carrying theposition transducers 40. Operation of the of device of FIGS. 3-5 isanalogous to that of the device of FIGS. 1 and 2.

The web cutting devices depicted in FIGS. 6-13 are applicable to cuttingfilter tipping paper (commonly known as "cork" paper) in a filtercigarette assembling machine. In this type of machine it is commonplaceto feed a web of gummed cork paper at a controlled speed onto a suctiondrum which is continuously rotating at a faster peripheral speed thanthe speed of the web. The cork web is transversely cut while on the drumto provide spaced sections which are subsequently conveyed at the speedof the drum. Cutting is usually achieved by means of knives mounted on aseparate roller which cooperates with the suction drum. The severed corksections travel with the drum to a position at which they are picked upby and subsequently rolled around axially aligned filter and tobaccoportions to unite them into a filter cigarette assembly. For furtherdetails of a filter cigarette assembling machine of this type referenceis directed to British patent specification No. 941832.

In the device of FIG. 6 a web 100 of filter tipping paper is fed at acontrolled speed by nip rolls 102 past a gumming roller 104 whichapplies adhesive (possibly in a predetermined pattern) to the paper. Forconvenience the adhesive will hereinafter be referred to as "gum",although it will be appreciated that not all suitable adhesives are truegums. The web 100 passes to a suction cutting drum 106 provided withknives 108 which cooperate with an ultrasonically-vibrated anvil 110 tosever the web into wrapper sections subsequently conveyed on the drum.Filter cigarette assemblies to be united are delivered by a fluted drum112 and are brought together with the wrapping sections on a rollingplate 114 at which the sections are wrapped and sealed around theassemblies. The united assemblies are subsequently conveyed away by afurther fluted drum 116.

The anvil 110 may be substantially similar to the anvil 12 in thedevices of FIGS. 1 and 2 or FIGS. 3-5, and be incorporated in a devicesimilar to the device 14. The anvil 110 needs continuous cleaning in theregion 118 as it will tend to collect some gum from the web 100 in thisregion. Cleaning can be achieved by a rotary brush and/or suctioncollection of excess gum on the anvil 110.

The knives 108 typically project about 0.2 mm above the general surfaceof the drum 106. In order to protect the filter cigarette assemblies atthe rolling plate 114 the knives 108 may be mounted in radial slides andactuated by a cam 120 so that they are extended in the region of theanvil 110 but retracted to a position at or below the level of the drum106 at the rolling plate.

Instead of using gummer 104 to apply adhesive to the web 100 upstream ofthe anvil 11 0, with attendant cleaning problems, a gummer 104A could beused for applying adhesive to the severed sections of the web. Thegummer 104A is synchronised with the passage of wrapper sections on thedrum 106, so that adhesive is applied to the sections and not to thedrum. Depending on the characteristics of the adhesive, a heater and/ordryer 105 may be required, in view of the closeness of the gummer 104Ato the rolling plate 114.

In the device of FIG. 7 parts similar to those in the device of FIG. 6have been given similar reference numbers. The web 100 is gummed by agummer 104 acting on its undersurface and is delivered to a suctionrolling drum 122 which is provided with fixed knives 124. As shown inFIG. 8, the pattern of gum 126 applied to the web 100 includes windows128 of ungummed paper. By arranging for suction ports on the drum 122 toapply suction only at positions corresponding to the windows 128,transfer of excessive amounts of gum to the surface of the drum can beavoided. A rotary brush 130 removes gum which remains on the knives 124and any small amounts deposited on the surface of the drum 122. Thewrapper sections severed from the web 100 are carried by the drum 122and transferred to a further suction drum 134 from where they arewrapped around assemblies to be united delivered to the rolling plate114. Note that in this arrangement gum does not collect on the anvil110. As a supplement or alternative to the rotary brush 130 a pivotedscraper blade 131 could be used. This could be cam-operated so as to belifted to avoid the knives 124. Alternatively a wheel with flexibleblades, i.e. a flap wheel, could be used.

In an alternative way of operating the embodiment of FIG. 7 the gummer104 is omitted and the web 100 is precoated with an adhesive (e.g. hotmelt or PVA) which is substantially dry by the time the web contacts thedrum 122 and which is reactivated by a heater 133 on the drum 134. Thebrush 130 should not then be necessary.

FIG. 9 shows a web cutting device employing an ultrasonically-vibratedrotating cylinder 140 comprising an annular piezoelectric core 142surrounded by a titanium alloy sleeve 144 which acts as a booster forthe ultrasonic vibrations. The cylinder 142 oscillates in acircumferential oscillation mode (as opposed to a radial or wallthickness changing mode). Cooling fluid is passed through the centre ofthe core 142.

A web 100 is delivered at a controlled speed by nip rolls 102 andreceives gum from a gummer 104. A suction cutting drum 146 provided withspaced cutting knives 148 is opposed to the cylinder 140 and cooperateswith it to produce cut wrapper sections which are conveyed away by thedrum 146 to a rolling plate (not shown). The surface of the titaniumalloy sleeve 144 is hardened to resist damage from the knives 148. Thedrum 146 and knives 148 may be similar to the drum 106 and knives 108 ofthe device shown in FIG. 6.

The cylinder 140 may be provided with suction instead of the drum 146 sothat the cut wrapper sections are conveyed away by the cylinder. In thiscase the uniting of the wrapper sections and filter cigarette assembliesmay take place at a rolling plate 150 cooperating directly with thecylinder 140 or at a rolling plate 152 cooperating with a furthersuction drum 154 which receives wrapper sections from the cylinder. Inthis last case the gummer 104 is replaced by a gummer 104A acting on theundersurface of the web 100. The suction regions of is the cylinder 140may be arranged to coincide with areas of ungummed web, as explainedwith reference to FIGS. 7 and 8. As compared with the previousembodiments the FIG. 9 arrangement has the advantage that the ultrasounddevice 140 is movable with the web 100.

FIG. 10 is aside view of a modified cylinder 160, which may replace thecylinder 140 in the device of FIG. 9. The cylinder 160 consists of atitanium alloy ultrasonic horn formed with an integral subshaft 162which is attached to an ultrasonic generator and booster (not shown).The generator and booster rotate at the speed of the cylinder 160, withslip ring electrical contacts and air supply (for suction on the surfaceof the cylinder and also for air cooling). The cylinder 160 is designedsuch that ultrasound vibrations generated along the axis of the cylinderare converted into vibrations perpendicular to this axis, i.e. radialvibrations. This transverse vibration may be supplemented by cantilevermounting of the cylinder 160 so that it has a resonant frequency withinthe range of the frequency of the ultrasonic vibration. Alternatively,the cylinder 160 may have a coaxial support shaft 161. The form of thecylinder 160 could be similar to the ultrasonic transducer disclosed inBritish patent specification No. 1524924, to which reference is directedfor details.

In the embodiment of FIGS. 9 and 10 the cylinders 140 and 160 need notbe the anvils: they could carry the cutting knives.

In the device shown in FIG. 11 a web 100 is delivered to a suctioncylinder 170 having two cutting stations defined by the end faces of twoultrasonic boosters 172 which are connected to a central commonultrasonic generator 174 which causes the faces of the boosters tovibrate in a radial direction relative to the cylinder 170. A knifecylinder 176 having one or more knives 178 cooperates with the cylinder170 so that the web 100 is cut when a knife is opposed to an end face ofone of the boosters 172. The wrapper sections severed from the web 100are conveyed by the cylinder 170 to a rolling plate 150. Alternatively,the web 100 is gummed on its undersurface by a gummer 104A and thesevered wrapper sections are transferred to a further suction drum 154for uniting filter assemblies at a rolling plate 152. The wrappersections could be conveyed by a modified cylinder 176 (provided withsuction) instead of by the cylinder 170, i.e. in a way similar to thatdescribed with reference to FIG. 9.

The device of FIG. 12 is similar to that of FIG. 11 except that thecylinder 170 is replaced by a modified ultrasonic cylinder 180, whichcomprises a central piezoelectric tubular core 182 forming part of anultrasonic generator, and a series of radial titanium spokes 184 formingultrasonic boosters and having their radially outermost faces hardenedand substantially flush with the general surface of the cylinder so asto form anvils against which the knives 178 operate. Cut wrappersections may be conveyed to a rolling plate 152 by way of a furthersuction drum 154, or directly to a rolling plate 150 if the web isgummed by an upper gummer 104A. In this latter case a brush 186 isprovided to remove excess gum from the knife drum 176 and knives 178.

FIG. 13 shows a sectional view of a knife drum 190 having knives 192cooperating with a stationary ultrasonic anvil 194. Thus the drum 190and anvil 194 may be similar to and replace the drum 122 and anvil 110in the device of FIG. 7, for example. Alongside the drum 190 arelaterally spaced control rings 196, which are ground to the same orsimilar diameter as that of the drum 190 measured at the outer edges ofthe knives 192 and act as a stop for the anvil 194 at times when a cutis not being made. The anvil 194 could be resiliently preloaded againstthe control rings 196: this can avoid having to make adjustments tocompensate for thermal expansion of the anvil during the periodfollowing start up.

Control rings similar to the rings 196 could be used with a rotaryultrasonic anvil, e.g. any of the cylinders 144, 160, 170, and 180,shown in FIGS. 9-2.

FIG. 14, which is not to scale, is an enlarged side view of a modifiedweb cutting device capable of sealing and cutting substantiallysimultaneously. The device is particularly usefully applied in theapparatus of FIGS. 1 and 2 or FIGS. 3-5, where usually the double plyweb 2 is sealed by separate web sealing rollers upstream of the cuttingrollers 4. Use of the device shown in FIG. 14 avoids the need forseparate sealing rollers.

A web 200, which may comprise a double ply web containing spaced regionsof infusible material, is advanced between a cutting and sealing roller202 and a stationary ultrasound anvil 204. The roller 202 carriescutting and sealing elements 206 which define the shape of the portionof web to be sealed and cut out. Thus the elements 206 may define anenclosed region, e.g. having a circular periphery similar to the edges 8in the FIG. 1 device, or could extend transversely so that onlytransverse cuts and seals (e.g. severing the web) are made by theelements 206. In this instance one or more longitudinal seals in the webto complete the enclosure of each portion to be cut out may be made byother means (not shown), preferably upstream of the roller 202.

The elements 206 comprise a narrow cutting edge 208 having a width ofabout 0.1 mm and a relatively wide shoulder 210 having a width of about4 mm. The edge 208 projects about 0.05 mm above the shoulder 210 and thelatter projects about 0.02 mm above the general circumference of theroller 202. The pressure and heat generated between the shoulder 210 ofthe element 206 and the ultrasonic anvil 204 causes sealing of thedouble ply web 200, which for this purpose may be formed from thermallyweldable material or may be preprinted at appropriate positions with anadhesive which is susceptible to activation or setting by application ofheat. The edge 208 provides a localised increased action against the web200 and anvil 204, sufficient to sever the web. The shoulder 210 neednot be flat, and could have a convex surface for effecting sealing ofthe webs.

FIG. 15 shows part of a modified roller 220, which may replace any ofthe rollers 144, 160, 170 or 180 in the previously-describedembodiments. The roller 220 includes anvils 222 formed at end faces ofan ultrasonic beam 226 which is cantilevered from an integral centralupstanding strut 228. A piezoelectric stack, forming an ultrasonicgenerator 230, is arranged between one arm of the beam 226 and anintegral base 232. The amplitude of the vibrations at the generator 230is effectively amplified at the anvils 222 by flexing of the beam 226about its connection to the strut 228. The roller 220 has additionalsimilar anvils 222 (not shown) arranged symmetrically around itscircumference. An additional piezoelectric stack could be provided onthe opposite side of the strut 228, to balance the stack forming thegenerator 230.

The device shown in FIGS. 16 and 17 has many similarities with thedevices of FIGS. 1 and 2 and FIGS. 3-5. The device includes anultrasound generator 316 mounted in a housing 320 and connected to ahorn or anvil 312 which is clamped to the housing at a nodal flange 322.The lower end of the anvil 312 is located just above the surface of asuction drum 350 which carries spaced knives 352 for severing successiveleading sections from a web 100, the drum including suction holes 354for retaining the severed web sections on the drum after cutting. Closeto the upstream edge of the lower end of the anvil 312 is an air nozzle356 including a slit 358 from which an air jet is directable at theregion of the surface of the drum 350 just upstream of and adjacent theanvil. The slit 358 extends for at least the width of the web 100, andpreferably for the width of the anvil 312. An air jet issuing from theslit 358 has been found beneficial in locating the web on the surface ofthe drum 350 just prior to severing between the knives 352 and theanvil.

The web 100 is gummed on its upper surface at a position upstream of thedrum 350, the web passing over a heating and/or drying element 360.Providing a bevelled or chamfered surface on the upstream lower edge ofthe anvil 312 reduces problems associated with build up of gum on theanvil. Where such a bevelled or chamfered upstream edge is provided forthe anvil 312 it is preferred to provide a similarly-shaped downstreamedge. The effect of the air jet issuing from the slit 358 in maintainingthe web on the drum 350 is also believed to be beneficial in reducingproblems with build up of gum on the anvil.

A simple web speed modulator 362 is shown in FIG. 17. This comprises anelement which is rotatable or reciprocable periodically and issynchronised with the drum 350 to deflect the web and so modulate thepath of the web 100 that it travels at the same speed as the drum at theinstant when a knife 354 is passing the anvil 312 but at a lower speedat other times.

The housing 320 is slidable in guideways 330 in an adjuster frame 370.The position of the housing 320, and hence of the anvil 312, relative tothe frame 370 is controlled by microadjusters or linear actuators 336.The frame 370 carries cam rollers 372 which bear on annular hardenedcircumferential inserts 374 carried by the drum 350. Load cylinders 376are arranged between a machine frame part 378 and the housing 320, thearrangement being such that the cylinders apply a predetermined loadthrough the housing and the frame 370 to the rollers 372. Themicroadjusters 336 thus effectively set the gap between the surface ofthe drum 350 (or more correctly the locus of the knives 352) and thelower edge of the anvil 312.

A device similar to that disclosed in FIGS. 16 and 17 may be used in theembodiments of FIGS. 6 or 7, or to replace the device of FIGS. 1 and 2or FIGS. 3-5 in any of the previously-described embodiments.

Although specific mention has been made of ultrasound generatorsincluding piezoelectric material the ultrasound could be generated inany convenient manner and using any suitable material. For examplemagnetostrictive material could be used: this may have advantages as itcan be structurally stronger than piezoelectic material.

We claim:
 1. Apparatus for making successive longitudinally-spaced cutsin a web, comprising means for moving the web, means for periodicallybringing a cutter into the region of the web, the cutter being carriedby a rotary drum and cooperating with an anvil in a cutting region, andmeans for producing high frequency relative vibration between the cutterand the web, so that the cutter makes at least one cut having at least aportion extending in a direction transverse the web, wherein the cutteris arranged to sever successive portions of the web from the remainderof the web, said rotary drum carrying a plurality of said cutters inequally spaced peripheral positions, said drum being provided withsuction means for retaining said portion in spaced positions betweensaid cutters on the periphery of said drum after severing, and means fortransferring said spaced portions from said drum at a position angularlydisplaced from said position at which said portions are severed from theweb, including adjustable means for mounting the anvil so as to adjustthe spacing between the anvil and the cutters, said adjustable meansincluding means determining said spacing including rotatable meansacting between the anvil and the drum.
 2. Apparatus as claimed in claim1, wherein the vibration producing means comprises an ultrasoundgenerator.
 3. Apparatus as claimed in claim 1 or claim 2, wherein theprimary amplitude of the vibration is transverse to the web. 4.Apparatus as claimed in claim 1, wherein the vibration producing meansproduces relative vibration between the cutter and the anvil. 5.Apparatus as claimed in claim 4, wherein the vibration producing meanscomprises an ultrasound generator linked to the anvil.
 6. Apparatus asclaimed in claim 5, wherein the anvil includes an end surface forcooperating with said cutter, said surface extending for the width ofthe web and having a relatively narrow dimension in the direction ofmovement of the web.
 7. Apparatus as claimed in claim 6, wherein saidsurface is bevelled at least along its edge which is upstream relativeto the direction of movement of the web.
 8. Apparatus as claimed inclaim 4, wherein said adjustable means includes at least one linearlymovable adjustment means.
 9. Apparatus as claimed in claim 5, whereinthe anvil comprises a rotary member and the ultrasound generator isarranged to produce vibrations which are radial relative to said rotarymember.
 10. Apparatus as claimed in claim 4, wherein the vibrationproducing means comprises an ultrasound generator linked to the cutter.11. Apparatus as claimed in claim 10, wherein the ultrasound generatoris arranged to produce vibrations which are radial relative to saidrotary drum.
 12. Apparatus as claimed in claim 9 or 11, wherein theultrasound generator is arranged to produce radial vibrations in anannular peripheral part of said rotary member or drum.
 13. Apparatus asclaimed in claim 9 or 11, wherein the ultrasound generator is arrangedto produce radial vibrations in at least one radially extending memberof said rotary member or drum.
 14. Apparatus as claimed in claim 4,further including means for directing an air jet in the vicinity of saidcutting region so as to assist in maintaining said web in a preferredcutting position in said region.
 15. Apparatus as claimed in claim 14,wherein said anvil is linked to an ultrasound generator, wherein saidair jet directing means is arranged to assist maintaining said web onthe surface of said rotary drum.
 16. Apparatus as claimed in claim 4,wherein the cutter is arranged to sever successive portions of the webfrom the remainder of the web.
 17. Apparatus as claimed in claim 16,wherein the cutter has a cutting edge arranged to sever portions ofpredetermined closed shape from the web.
 18. Apparatus as claimed inclaim 16 or claim 17, wherein the web comprises at least two layers ofmaterial carrying spaced doses of material to be packaged between thelayers and said severed portions of the web correspond to individualpackages containing said material to be packaged.
 19. Apparatus asclaimed in claim 18, including means for sealing the web adjacent atleast part of the peripheral margin of the severed portions. 20.Apparatus as claimed in claim 19, wherein said sealing is performedsubstantially simultaneously with the severing operation of said cutter.21. Apparatus as claimed in claim 20, wherein said sealing and severingoperations are carried out with the assistance of ultrasound. 22.Apparatus as claimed in claim 21, including a cutting and sealingelement having a first flat part for sealing a margin of a portion ofthe web to be severed and a narrow edge part abutting said flat part forsevering said portion.
 23. Apparatus as claimed in claim 1, includingmeans for cleaning said cutters at a position downstream of said cuttingregion.
 24. Apparatus as claimed in claim 1 or 23, including means forperiodically moving said cutters in a direction which is substantiallyradial relative to said drum, so as to retract the cutter during part ofeach revolution of the drum.
 25. Apparatus for making successivelongitudinally-spaced cuts in a web, comprising means for moving theweb, means for periodically bringing a cutter into the region of theweb, the cutter being carried by a rotary drum and cooperating with ananvil in a cutting region, and adjustable means for mounting the anvilso as to adjust the spacing between the anvil and the cutters, saidadjustable means including means determining said spacing includingrotatable means acting between the anvil and the drum, and means forproducing high frequency relative vibration between the cutter and theweb, so that the cutter makes at least one cut having at least a portionextending in a direction transverse of the web, wherein the cutter has acutting edge arranged to sever portions of predetermined close shapefrom the web, the web comprising at least two layers of materialcarrying spaced doses of material to be packaged between the layers andsaid severed portions of the web corresponding to individual packagescontaining said material to be packaged.
 26. Apparatus as claimed inclaim 1 or 9, including a further rotary drum arranged to receive saidsections of the web from said rotary drum.
 27. Apparatus as claimed inclaim 1, wherein said rotatable means includes roller means supportingthe anvil and running on the surface of said drum.
 28. A method asclaimed in claim 27, wherein at least part of the peripheral margin ofthe package is sealed with the assistance of ultrasound substantiallysimultaneously with the cutting step.
 29. Apparatus as claimed in claim28, wherein the adjustable means comprises a first frame member carryingthe anvil, a second frame member carrying roller means contacting thedrum, and means for adjustably mounting the first frame member relativeto said second frame member.
 30. Apparatus as claimed in claim 28,wherein said rotatable means includes roller means supporting the anviland running on the surface of said drum.
 31. Apparatus for makingsuccessive longitudinally-spaced cuts in a web, comprising means formoving the web, means for periodically bringing a cutter into the regionof the web, the cutter being carried by a rotary drum and cooperatingwith an anvil in a cutting region, ultrasound generator means connectedto said anvil for producing high frequency relative vibration betweenthe cutter and the web, so that the cutter makes at least one cut havingat least a portion extending in a direction transverse of the web, thecutter being arranged to sever successive portions of the web from theremainder of the web, said rotary drum carrying a plurality of saidcutters in equally spaced peripheral positions and being provided withsuction means for retaining portions in said spaced positions betweensaid cutters on the periphery of said drum after severing, means fortransferring said spaced portions from said drum at a position angularlydisplaced from the position at which said portions are severed from theweb, the ultrasound generator means and anvil being supported by a firstframe member which is adjustably supported by a second frame membercarrying roller means which contact said rotary drum and determine theposition of the second frame member relative to said cutters, andpositional adjustable means for setting the position of the first framemember relative to the second frame member, whereby the spacing betweenthe anvil and the cutters may be precisely determined.
 32. Apparatus asclaimed in claim 31, wherein the loading means is provided for ensuringcontact between the roller means of said second frame member and saiddrum, said loading means acting directly on said first frame memberwhich transmits the loading force to said second member.
 33. Apparatusas claimed in claim 32, wherein the spacing adjustable means comprises afirst frame member carrying the anvil, a second frame member carryingroller means contacting the drum, and means for adjustably mounting thefirst frame member relative to said second frame member.
 34. Apparatusas claimed in claim 31, 32 or 33, wherein the position of the anvilrelative to the cutter is determined by at least one linearly movableadjustment means.
 35. Apparatus as claimed in claim 1 or 32, furtherincluding means for applying adhesive to said portions after they havebeen severed from the web.
 36. Apparatus as claimed in claim 32, whereinsaid first frame member is slidably movable relative to said secondframe member in a direction which is substantially radial relative tosaid drum, said positional adjustable means acting in opposition to saidloading means to determine the position of said first frame memberrelative to said second frame member.